Electrochemical, Structural and Magnetic Analysis of Electrodeposited CoCu/Cu Multilayers: Influence of Cu Layer Deposition Potential

The electrochemical, structural and magnetic properties of CoCu/Cu multilayers electrodeposited at different cathode potentials were investigated from a single bath. The Cu layer deposition potentials were selected as \(-\,0.3,\,\hbox {V}\) \(-\,0.4\,\,\hbox {V}\), and \(-\,0.5\,\hbox {V}\) with respect to saturated calomel electrode (SCE) while the Co layer deposition potential was constant at \(-\,1.5\,\hbox {V}\) versus SCE. For the electrochemical analysis, the current-time transients were obtained. The amount of noble non-magnetic (Cu) metal materials decreased with the increase of deposition potentials due to anomalous codeposition. Further, current-time transient curves for the Co layer deposition and capacitance were calculated. In the structural analysis, the multilayers were found to be polycrystalline with both Co and Cu layers adopting the face-centered cubic structure. The (111) peak shifts towards higher angle with the increase of the deposition potentials. Also, the lattice parameters of the multilayers decrease from 0.3669 nm to 0.3610 nm with the increase of the deposition potentials from \(-\,0.3\,\hbox {V}\) to \(-\,0.5\,\hbox {V}\), which corresponds to the bulk values of Cu and Co, respectively. The electrochemical and structural results demonstrate that the amount of Co atoms increased and the Cu atoms decreased in the layers with the increase of deposition potentials due to anomalous codeposition. For magnetic measurements, the saturation magnetizations, \(M_s\) obtained from the magnetic curves of the multilayers were obtained as 212 kA/m, 276 kA/m, and 366 kA/m with \(-\,0.3\,\hbox {V}\), \(-\,0.4\,\hbox {V}\), and \(-\,0.5\,\hbox {V}\) versus SCE, respectively. It is seen that the \(M_s\) values increased with the increase of the deposition potentials confirming the increase of the Co atoms and decrease of the Cu amount. The results of electrochemical and structural analysis show that the deposition potentials of non-magnetic layers plays important role on the amount of magnetic and non-magnetic materials in the layers and thus on the magnetic properties of the multilayers.